text: /**
   * Copyright (c) 2017 - 2018, Nordic Semiconductor ASA
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form, except as embedded into a Nordic
   *    Semiconductor ASA integrated circuit in a product or a software update for
   *    such product, must reproduce the above copyright notice, this list of
   *    conditions and the following disclaimer in the documentation and/or other
   *    materials provided with the distribution.
   *
   * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
   *    contributors may be used to endorse or promote products derived from this
   *    software without specific prior written permission.
   *
   * 4. This software, with or without modification, must only be used with a
   *    Nordic Semiconductor ASA integrated circuit.
   *
   * 5. Any software provided in binary form under this license must not be reverse
   *    engineered, decompiled, modified and/or disassembled.
   *
   * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
   * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
  #include <stdbool.h>
  #include "nrf_dfu_types.h"
  #include "nrf_dfu_settings.h"
  #include "nrf_dfu_utils.h"
  #include "nrf_bootloader_info.h"
  #include "nrf_crypto.h"
  #include "nrf_assert.h"
  #include "dfu-cc.pb.h"
  #include "nrf_dfu_ver_validation.h"
  
  #define NRF_LOG_MODULE_NAME nrf_dfu_ver_validation
  #include "nrf_log.h"
  NRF_LOG_MODULE_REGISTER();
  
  
  /** @brief Macro for reading the Firmware ID of a SoftDevice at a given base address.
   */
  #ifndef _SD_FWID_GET
  #define _SD_FWID_GET(baseaddr)         SD_OFFSET_GET_UINT16(baseaddr, 0x0C)
  #endif
  
  #define EXT_ERR(err) (nrf_dfu_result_t)((uint32_t)NRF_DFU_RES_CODE_EXT_ERROR + (uint32_t)err)
  
  static bool sd_req_check(uint32_t const * p_sd_req, uint8_t sd_req_cnt)
  {
      bool result = false;
      for (uint8_t i = 0; i < sd_req_cnt; i++)
      {
          if (p_sd_req[i] == _SD_FWID_GET(MBR_SIZE))
          {
              // Found a matching sd_req field. sd_req is ok.
              result = true;
              break;
          }
      }
      return result;
  }
  
  static bool sd_req_ok(dfu_init_command_t const * p_init)
  {
      ASSERT(p_init != NULL);
      bool result;
  #ifdef BLE_STACK_SUPPORT_REQD
      // The bootloader needs the SoftDevice, so disabling NRF_DFU_APP_DOWNGRADE_PREVENTION
      // should not be applied to SoftDevice updates.
      const bool prevent_downgrade = NRF_DFU_APP_DOWNGRADE_PREVENTION || (p_init->type == DFU_FW_TYPE_SOFTDEVICE);
  #else
      const bool prevent_downgrade = NRF_DFU_APP_DOWNGRADE_PREVENTION;
  #endif
  
      if (SD_PRESENT)
      {
          if (p_init->sd_req_count && (p_init->sd_req[0] != SD_REQ_APP_OVERWRITES_SD))
          {
              result = sd_req_check(p_init->sd_req, p_init->sd_req_count);
          }
          else if (p_init->type == DFU_FW_TYPE_APPLICATION)
          {
              // The application wants to overwrite the SoftDevice.
              if (prevent_downgrade && (p_init->sd_req_count > 1) && (p_init->sd_req[0] == SD_REQ_APP_OVERWRITES_SD))
              {
                  // The application can overwrite the SD if sd_req[0] == 0 and table has the fwid of the current SD.
                  result = sd_req_check(p_init->sd_req, p_init->sd_req_count);
  
                  // Prevent BLE bootloaders from allowing applications overwriting the SoftDevice.
  #ifdef BLE_STACK_SUPPORT_REQD
                  result = false;
  #endif // BLE_STACK_SUPPORT_REQD
              }
              else
              {
                  result = true;
              }
          }
          else
          {
              // Don't allow SoftDevice updates which assume no SD is present already.
              result = !prevent_downgrade || (p_init->type != DFU_FW_TYPE_SOFTDEVICE);
          }
      }
      else
      {
          if (p_init->sd_req_count && (p_init->sd_req[0] != SD_REQ_APP_OVERWRITES_SD))
          {
              // Fail if there is no SD and the update requires SD.
              result = false;
          }
          else
          {
              // If there is no SD and update has SD it is accepted only if it has a fw_version.
              result = !prevent_downgrade || p_init->has_fw_version;
          }
      }
      return result;
  }
  
  static bool fw_hash_type_ok(dfu_init_command_t const * p_init)
  {
      ASSERT(p_init != NULL);
  
      return (p_init->hash.hash_type == DFU_HASH_TYPE_SHA256);
  }
  
  static bool fw_version_required(dfu_fw_type_t new_fw_type)
  {
      bool result = true;
  
      if (new_fw_type == DFU_FW_TYPE_SOFTDEVICE)
      {
          result = false; // fw_version is optional in SoftDevice updates. If present, it will be checked against the app version.
      }
      else if (new_fw_type == DFU_FW_TYPE_APPLICATION)
      {
          result = NRF_DFU_APP_DOWNGRADE_PREVENTION; // fw_version is configurable in app updates.
      }
  
      return result;
  }
  
  
  static bool fw_type_ok(dfu_init_command_t const * p_init)
  {
      ASSERT(p_init != NULL);
  
      return ((p_init->has_type)
              && (  (p_init->type == DFU_FW_TYPE_APPLICATION)
                 || (p_init->type == DFU_FW_TYPE_SOFTDEVICE)
                 || (p_init->type == DFU_FW_TYPE_BOOTLOADER)
                 || (p_init->type == DFU_FW_TYPE_SOFTDEVICE_BOOTLOADER)));
  }
  
  
  // This function assumes p_init->has_fw_version.
  static bool fw_version_ok(dfu_init_command_t const * p_init)
  {
      ASSERT(p_init != NULL);
      ASSERT(p_init->has_fw_version);
  
      if (  (p_init->type == DFU_FW_TYPE_APPLICATION)
         || (p_init->type == DFU_FW_TYPE_SOFTDEVICE))
      {
          return ((p_init->fw_version >= s_dfu_settings.app_version) || !NRF_DFU_APP_DOWNGRADE_PREVENTION);
      }
      else
      {
          return  (p_init->fw_version > s_dfu_settings.bootloader_version);
      }
  }
  
  nrf_dfu_result_t nrf_dfu_ver_validation_check(dfu_init_command_t const * p_init)
  {
      nrf_dfu_result_t ret_val = NRF_DFU_RES_CODE_SUCCESS;
      if (!fw_type_ok(p_init))
      {
          NRF_LOG_ERROR("Invalid firmware type.");
          ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_INIT_COMMAND_INVALID);
      }
      else if (!fw_hash_type_ok(p_init))
      {
          NRF_LOG_ERROR("Invalid hash type.");
          ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_WRONG_HASH_TYPE);
      }
      else if (!NRF_DFU_DEBUG ||
              (NRF_DFU_DEBUG && ((p_init->has_is_debug == false) || (p_init->is_debug == false))))
      {
          if (p_init->has_hw_version == false)
          {
              NRF_LOG_ERROR("No HW version.");
              ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_INIT_COMMAND_INVALID);
          }
          else if (p_init->hw_version != NRF_DFU_HW_VERSION)
          {
              NRF_LOG_WARNING("Faulty HW version.");
              ret_val = EXT_ERR( NRF_DFU_EXT_ERROR_HW_VERSION_FAILURE);
          }
          else if (!sd_req_ok(p_init))
          {
              NRF_LOG_WARNING("SD req not met.");
              ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_SD_VERSION_FAILURE);
          }
          else if (p_init->has_fw_version)
          {
              if (!fw_version_ok(p_init))
              {
                  NRF_LOG_WARNING("FW version too low.");
                  ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_FW_VERSION_FAILURE);
              }
          }
          else
          {
              if (fw_version_required(p_init->type))
              {
                  NRF_LOG_ERROR("FW version missing.");
                  ret_val = EXT_ERR(NRF_DFU_EXT_ERROR_INIT_COMMAND_INVALID);
              }
          }
      }
      return ret_val;
  }
  